System and method for massive multiple-input multiple-output communications

ABSTRACT

A transmitter adapted for massive multiple-input multiple-output (M-MIMO) operation includes a first set of power amplifiers (PAs) that amplifies a first signal to produce an amplified first signal, and a second set of PAs that amplifies a second signal to produce an amplified second signal, wherein PAs in the first set of PAs are different from PAs in the second set of PAs. The transmitter includes an antenna array operatively coupled to the first set of PAs and the set of second PAs, the antenna array including a plurality of transmit antennas, wherein the antenna array transmits one or more of the amplified signals.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. patent application Ser. No.14/637,100, filed Mar. 3, 2015, entitled “System and Method for MassiveMultiple-Input Multiple-Output Communications,” which claims the benefitof U.S. Provisional Application No. 61/949,812, filed on Mar. 7, 2014,entitled “Radio Frequency Structure for Massive Multiple-InputMultiple-Output (MIMO),” all of which applications are herebyincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to digital communications, andmore particularly to a system and method for massive multiple-inputmultiple-output (M-MIMO) communications.

BACKGROUND

Multiple-input multiple-output (MIMO) communications systems usemultiple antennas at both the transmitter and receiver of a wirelessnetwork to improve signal performance (e.g., spectral efficiency, linkreliability, and the like) through the exploitation of spatialdiversity. More specifically, MIMO offers significant increases in datathroughput and link range without requiring additional bandwidth orincreased transmit power. Large-scale antenna systems that utilize MIMOtechniques are commonly referred to as Massive MIMO (M-MIMO) systems,and they typically have more service-antennas than the number of activeterminals that they service. Extra antennas help by focusing energy intosmaller regions of space to bring improvements in throughput andradiated energy efficiency. M-MIMO is a particular case of multi-userMIMO (MU-MIMO) with narrow transmission beams that enable simultaneousservice to multiple users. Other benefits of M-MIMO include theextensive use of inexpensive low-power components, reduced latency,simplification of the media access control (MAC) layer, robustness tointentional jamming, and the like. Accordingly, techniques forintegrating M-MIMO systems into next-generation wireless networks aredesired.

SUMMARY

Example embodiments of the present disclosure which provide a system andmethod for M-MIMO communications.

In accordance with an example embodiment of the present disclosure, atransmitter adapted for massive multiple input multiple output (M-MIMO)operation is provided. The transmitter includes a first set of poweramplifiers (PAs) that amplifies a first signal to produce an amplifiedfirst signal, and a second set of PAs that amplifies a second signal toproduce an amplified second signal, wherein PAs in the first set of PAsare different from PAs in the second set of PAs. The transmitterincludes an antenna array operatively coupled to the first set of PAsand the set of second PAs, the antenna array including a plurality oftransmit antennas, where the antenna array transmits one or more of theamplified signals.

In accordance with another example embodiment of the present disclosure,an evolved NodeB (eNB) adapted for massive multiple input multipleoutput (M-MIMO) operation is provided. The eNB includes an antennaarray, and a transmitter operatively coupled to the antenna array. Theantenna array includes a plurality of transmit antennas. The transmitteramplify a first signal with a first set of power amplifiers (PAs),amplifies a second signal with a second set of PAs, and transmits atleast one of the amplified first signal and the amplified second signalover the antenna array during a first time interval.

In accordance with another example embodiment of the present disclosure,a method for operating a transmitter is provided. The method includesdetermining, by the transmitter, which one of a first signal and asecond signal is to be transmitted during a first time interval,amplifying, by the transmitter, the first signal with a first set ofpower amplifiers (PAs) to produce an amplified first signal in responseto determining that the first signal is to be transmitted during thefirst time interval, thereby producing an amplified first signal, andamplifying, by the transmitter, the second signal with a second set ofPAs to produce an amplified second signal in response to determiningthat the second signal is to be transmitted during the first timeinterval. The method includes transmitting, by the transmitter, one ofthe amplified first signal and the amplified second signal during thefirst time interval.

In accordance with another example embodiment of the present disclosure,a method for operating a receiving device is provided. The methodincludes receiving, by the receiving device, an amplified first signaland an amplified second signal during a time interval, wherein theamplified first signal and the amplified second signal are transmittedby an antenna array, wherein the amplified first signal is amplified bya first set of power amplifiers (PAs) and the amplified second signal isamplified by a second set of PAs, and wherein PAs in the first set ofPAs are different from PAs in the second set of PAs, and processing, bythe receiving device, the first amplified signal and the secondamplified signal as received.

One advantage of an embodiment is that the use of separate poweramplifiers to provide optimized coverage for different types oftransmissions, including broadcast and unicast. Furthermore, theseparate power amplifiers may be powered down when not used, therebyhelping to reduce power consumption.

A further advantage of an embodiment is that the separate poweramplifiers may share antennas. Therefore, the number of antennas doesnot need to be increased, thereby helping to maintain design simplicityand lower implementation costs.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawing, in which:

FIG. 1 illustrates an example communications system according to exampleembodiments described herein;

FIG. 2 illustrates a first example transmitter architecture according toexample embodiments described herein;

FIG. 3a illustrates a first example RF band for M-MIMO according toexample embodiments described herein;

FIG. 3b illustrates a second example RF band for M-MIMO according toexample embodiments described herein;

FIG. 4 illustrates a second example transmitter architecture accordingto example embodiments described herein;

FIG. 5a illustrates a third example RF band for M-MIMO according toexample embodiments described herein;

FIG. 5b illustrates a fourth example RF band for M-MIMO according toexample embodiments described herein;

FIG. 6 illustrates a flow diagram of example operations occurring in acontroller as the controller sets PA state according to exampleembodiments described herein;

FIG. 7 illustrates a flow diagram of example operations occurring in aUE according to example embodiments described herein; and

FIG. 8 illustrates an example communications device according to exampleembodiments described herein.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The operating of the current example embodiments and the structurethereof are discussed in detail below. It should be appreciated,however, that the present disclosure provides many applicable inventiveconcepts that can be embodied in a wide variety of specific contexts.The specific embodiments discussed are merely illustrative of specificstructures of the disclosure and ways to operate the disclosure, and donot limit the scope of the disclosure.

One embodiment of the disclosure relates to massive multiple-inputmultiple-output (M-MIMO) communications. For example, a transmitteramplifies first signals with a first power amplifier (PA) set to produceamplified first signals, and amplifies second signals with a second PAset to produce amplified second signals. The transmitter also transmitsat least one of the amplified first signals and the amplified secondsignals using an antenna array including a plurality of transmit antennaduring a first time interval.

The present disclosure will be described with respect to exampleembodiments in a specific context, namely communications systems thatuse large antenna arrays and M-MIMO operation to support beamforminggain. The disclosure may be applied to standards compliantcommunications systems, such as those that are compliant with ThirdGeneration Partnership Project (3GPP), IEEE 802.11, and the like,technical standards, and non-standards compliant communications systems,that support M-MIMO operation.

FIG. 1 illustrates an example communications system 100. Communicationssystem 100 may be used for communicating data. Communications system 100may include an evolved NodeB (eNB) 110 having a coverage area 101, aplurality of user equipments (UEs) 120, and a backhaul network 130. eNB110 may comprise any component capable of providing wireless access byestablishing uplink (dashed line) and/or downlink (solid line)connections with UEs 120, such as a base station, a NodeB (NB), anaccess point (AP), a femtocell, a picocell, a relay node, and otherwirelessly enabled devices. UEs 120 may comprise any component capableof establishing a wireless connection with eNB 110, such as asubscriber, a mobile, a mobile station (STA), a terminal, a user, orother wirelessly enabled devices. Backhaul network 130 may be anycomponent or collection of components that allow data to be exchangedbetween eNB 110 and a remote end (not shown). In some embodiments,communications system 100 may comprise various other wireless devices,such as relays, low power nodes, etc.

While it is understood that communications systems may employ multipleeNBs capable of communicating with a number of UEs, only one eNB, andtwo UEs are illustrated for simplicity.

As shown in FIG. 1, eNB 110 may make use of M-MIMO to communicate withUEs 120. In communications systems that use M-MIMO, the number oftransmit antennas used by the eNBs will exceed the number ofsimultaneously served UEs to allow for UE separation and data coveragevia beamforming gain. Typically, when the number of transmit antennasused by the eNBs exceed 8, the eNBs may be considered to be usingM-MIMO. Generally, when the number of transmit antennas at an eNBincreases, communications links (e.g., M-MIMO, MU-MIMO, and the like)and communications with UEs are easier to establish. Higher ratios oftransmit antennas to simultaneously served UEs may achieve increasedcoverage, while lower ratios of transmit antennas to simultaneouslyserved UEs may achieve increased throughput. Therefore, a communicationssystem may trade throughput for coverage (and vice versa) by adjustingthe number of active UEs scheduled to receive simultaneoustransmissions.

Notably, system information (e.g., control information, schedulinginformation, and the like) is generally broadcast to many UEs indifferent spatial locations, and consequently it is typically desirableto maintain a uniform wave radiation pattern for broadcast channels sothat acceptable signal to noise ratios (SNR) can be maintained over theentirety of the coverage area of the cell. Furthermore, for UEs thathave not performed their initial random access procedure, the networkdoes not know their location; hence the broad coverage area of broadcastchannels may simplify the initial random access procedure. In general,broadcast channels convey transmissions over the entirety orsubstantially the entirety of a coverage area of the cell. Conversely,unicast signals can derive beamforming-gain performance benefits byvirtue of spatial selectivity, e.g., by achieving higher SNR ratios atthe location of an intended receiver at the expense of lower SNR ratiosat other locations. In other words, unicast signals are transmitted to aspecific UE, a group of UEs where the signal is labeled for the group ofUEs, as well as other situations wherein the signal is transmitted to asubset of all possible recipients. It is noted that when a transmissionis transmitted to more than one recipient, but not all recipients, thetransmission may be referred to as a multicast.

Conventional M-MIMO techniques use the same transmission drive circuitry(e.g., same amplifier set) to emit the unicast and broadcast signals,which can result in a coverage gap between the broadcast and unicastchannels. The coverage gap may be approximately equal to the M-MIMObeamforming gain for near ideal isotropic radiation patterns. Moreover,to achieve near ideal isotropic radiation patterns the powerdistribution among antennas will have to be uneven, which furtherreduces coverage. Typically, uneven power amplifier output is asignificant problem. In a unicast scenario, the output power of eachpower amplifier is approximately the same, so the power amplifiers aredesigned to have the same power rating. However, in the broadcastscenario, the broadcast radiation pattern results in different poweroutput distribution, so some power amplifiers are not fully utilized.Accordingly, techniques for allowing M-MIMO systems to efficientlycommunicate broadcast and unicast signals simultaneously withoutsignificant coverage gaps and/or uneven power outputs are desired.

Aspects of this disclosure use multiple power amplifier sets tocommunicate over a M-MIMO antenna array in order to improve signalperformance when simultaneously emitting unicast and broadcast signals.In some embodiments, one power amplifier set is used for amplifyingbroadcast signals, and another power amplifier set is used foramplifying unicast signals. The amplified unicast and broadcast signalsare then combined, e.g., using radio frequency (RF) combiners, and thecombination signal is broadcast using a portion of the M-MIMO array. Inone embodiment, the broadcast signals carry system information (e.g.,control, scheduling, and the like), while the unicast signals carrynon-system information (e.g., data, and the like). Embodiments of thisdisclosure maintain transmit diversity for broadcast signals withoutimpacting the beam-forming gain experienced by unicast signals. In someembodiments, the broadcast power amplifier set is turned off (or powereddown) during intervals in which broadcast signals are not being emitted.In some embodiments, the broadcast power amplifiers may require lessfunctionality than those used in other systems (e.g., may only need totransmit over certain sub-bands), which may allow for implementation ofless complex and/or smaller power amplifiers (e.g., less expensivecomponents) than those used in other systems, e.g., conventional M-MIMOand non-M-MIMO networks. Aspects of the disclosure improve spatialdiversity for broadcast signals by using antennas with largegeographical separation as broadcast antennas.

FIG. 2 illustrates a first example transmitter architecture 200.Transmitter architecture 200 provides comparable (to data unicasts)coverage for cell-wide system information broadcasts. Transmitterarchitecture 200 may be implemented in infrastructure equipment, such aseNBs, APs, base stations, NBs, femtocells, picocells, and the like. Asshown in FIG. 2, transmitter architecture 200 includes different poweramplifier (PA) sets for broadcast transmissions and unicasttransmissions. PAs in the PA set used for broadcast transmissions(broadcast transmission PAs) are shown in FIG. 2 as large cross hatchedtriangles, such as PA 205 and PA 207, while PAs in the PA set used forunicast transmissions (unicast transmission PAs) are shown as smalltriangles, such as PA 210, PA 212, and PA 214. According to an exampleembodiment, the PA set for broadcast transmissions includes one or morePAs for each antenna in a subset of the M-MIMO array and the PA set forunicast transmissions includes one PA for each antenna in the M-MIMOarray. It is noted that it is possible to have more than one PA from thePA set per antenna in the M-MIMO array. According to another exampleembodiment, the PA set for broadcast transmissions includes PAs forfewer than all antennas in the M-MIMO array. As an illustrative example,transmitter architecture 200 includes 2 broadcast transmission PAs (PAs205 and 207) and N unicast transmission PAs (where N is the number ofantennas in the M-MIMO array). The 2 broadcast transmission PAs may beconnected to antennas at or near opposite ends of the M-MIMO array (inother words, there is large physical separation between the antennas) toprovide spatial diversity.

Transmitter architecture 200 also includes RF combiners, such as RFcombiner 215 and RF combiner 217, which combines output signals frombroadcast transmission PAs and unicast transmission PAs. As an example,RF combiner 215 combines output signals from PA 205 and PA 210. Outputof the RF combiners may be provided to antennas in the M-MIMO array,such as antenna 220, and antenna 224.

The unicast signals and the broadcast signals may be transmittedsimultaneously. According to an example embodiment, the unicast signalsand the broadcast signals are communicated over different frequencybands. The broadcast transmission PAs may be adapted for narrow bandbroadcast transmission, while the unicast transmission PAs may beadapted for broadband unicast transmissions.

According to an example embodiment, the PA set used for unicasttransmissions may include PAs that are configured for beamforming orbroadcast based transmission, while the PA set used for broadcasttransmission may include PAs that are configured for broadcast basedtransmission. As an illustrative example, the unicast transmission PAsmay include a relatively large number of low power PAs, while thebroadcast transmission PAs may include comparatively fewer high powerPAs.

Transmitter architecture 200 may include a controller 230. Controller230 may be coupled to some or all of the PAs and control theiroperation, e.g., turn individual PAs power on or power off (or similarlypower-up or power-down). As an illustrative example, controller 230 mayturn the PAs off when they are not being used to help reduce powerconsumption. According to an example embodiment, controller 230 may becoupled to the broadcast transmission PAs. According to another exampleembodiment, controller 230 may be coupled to both the broadcasttransmission PAs and the unicast transmission PAs.

FIG. 3a illustrates a first example RF band 300 for M-MIMO. According toan example embodiment, broadcast transmissions are communicated vianarrowband transmissions, while unicast transmissions are communicatedvia broadband transmissions, e.g., over portions of the frequencyspectrum not occupied by the broadcast transmissions. As shown in FIG.3a , RF band 300 includes a first unicast band 305, a broadcast band310, and a second unicast band 315. Broadcast band 310 may be smaller(e.g., fewer communications system resources) than first unicast band305 and/or second unicast band 315. As an illustrative example, in a 10MHz 3GPP LTE compliant communications system, broadcast band 310occupies 6 central resource blocks out of a RF band of 350 resourceblocks. Although shown in FIG. 3a as being positioned between the twounicast bands, broadcast band 305 may be located anywhere in thefrequency spectrum, such as at the beginning or end of the frequencyspectrum. Furthermore, there may be multiple broadcast bands,distributed in the frequency spectrum. Therefore, the illustration anddiscussion of a single broadcast band located in between two unicastbands should not be construed as being limiting to either the scope orthe spirit of the example embodiments.

FIG. 3b illustrates a second example RF band 350 for M-MIMO. Accordingto an example embodiment, broadcast transmissions are transmitted overfewer than all time intervals and the broadcast transmission PAs may bepowered down during intervals in which broadcast transmissions are notbeing made. During such intervals, unicast transmissions may becommunicated over portions of the frequency spectrum that are otherwisereserved for the broadcast transmissions. As shown in FIG. 3b , RF band350 includes a single unicast band 355 for the transmission of unicasttransmissions by the unicast transmission PAs.

FIG. 4 illustrates a second example transmitter architecture 400.Transmitter architecture 400 provides comparable (to data unicasts)coverage for cell-wide system information broadcasts. Transmitterarchitecture 400 may be implemented in infrastructure equipment, such aseNBs, APs, base stations, NBs, femtocells, picocells, and the like. Asshown in FIG. 4, transmitter architecture 400 uses two PAs to achievesystem wide broadcasts, with high power PAs being used for unicasts aswell. For the most part, unicast transmissions are transmitted overdifferent antennas than broadcast transmissions in the M-MIMO array.However, the high power PAs used for broadcasts are also used forunicasts. As an example, both broadcast transmission PAs 405 and 407, aswell as unicast transmission PAs 410 and 412, transmit unicasttransmissions using antennas 415-421 of the M-MIMO array, while onlybroadcast transmission PAs 405 and 407 transmit broadcast transmissionsusing antennas 415 and 421.

FIG. 5a illustrates a third example RF band 500 for M-MIMO. According toan example embodiment, broadcast transmissions are communicated vianarrowband transmissions, while unicast transmissions are communicatedvia broadband transmissions, e.g., over portions of the frequencyspectrum not occupied by the broadcast transmissions. As shown in FIG.5a , RF band 500 includes a first unicast band 505, a broadcast band510, and a second unicast band 510.

FIG. 5b illustrates a fourth example RF band 550 for M-MIMO. Accordingto an example embodiment, broadcast transmissions are transmitted overfewer than all time intervals and the broadcast transmission PAs may beused to make unicast transmissions during intervals in which broadcasttransmissions are not being made. During such intervals, unicasttransmissions may be communicated over portions of the frequencyspectrum that are otherwise reserved for the broadcast transmissions. Asshown in FIG. 5b , RF band 550 includes a single unicast band 555 forthe transmission of unicast transmissions by the unicast transmissionPAs and the broadcast transmission PAs. Such a situation may beparticularly well adapted for high mobility UEs since the transmissionsof the broadcast transmission PAs can occupy substantially the entiretyof the coverage area, making it more likely that the transmissions ofthe broadcast transmission PAs cover the high mobility UEs.

FIG. 6 illustrates a flow diagram of example operations 600 occurring ina controller as the controller sets PA state. Operations 600 may beindicative of operations occurring in a controller, such as controller230, as the controller sets PA state.

Operations 600 may begin with the controller performing a check todetermine if it is in a broadcast interval (block 605). In other words,the controller is performing a check to determine if the broadcasttransmission PAs are to be used to make broadcast transmissions. If itis in a broadcast interval, the controller may power up the broadcasttransmission PAs or ensure that the broadcast transmission PAs remainpowered on if they are already on (block 610). If it is not in abroadcast interval, the controller may power down the broadcasttransmission PAs (block 615). The controller may return to block 605 torepeat the check to determine if it is in the broadcast interval.

FIG. 7 illustrates a flow diagram of example operations 700 occurring ina UE. Operations 700 may be indicative of operations occurring in a UE,such as UE 120, as the UE receives transmissions from a M-MIMO array.

Operations 700 may begin with the UE receiving a broadcast signal (block705). The broadcast signal may be non-beamformed and transmitted fromtransmit antennas coupled to broadcast transmission PAs. The broadcastsignal may be non-UE specific signal. Alternatively, the broadcastsignal may be a UE specific signal. The UE may also receive a unicastsignal (block 710). The unicast signal may be beamformed and transmittedfrom transmit antennas coupled to unicast transmission PAs. The unicastsignal may be a UE specific signal. The UE may process the broadcastsignal and the unicast signal (block 715).

FIG. 8 illustrates an example communications device 800. Communicationsdevice 800 may be an implementation of a communications controller, suchas an eNB, a base station, a NodeB, a controller, and the like, in aM-MIMO configuration. Communications device 800 may be used to implementvarious ones of the embodiments discussed herein. As shown in FIG. 8, atransmitter 805 is configured to transmit unicast transmissions,broadcast transmissions, and the like. Transmitter 805 includes a set ofunicast transmission PAs 807 and a set of broadcast transmission PAs809. The unicast transmission PAs are more numerous than the broadcasttransmission PAs, but the broadcast transmission PAs are, on anindividual basis, more powerful than the unicast transmission PAs. RFcombiners are configured to combine outputs of a subset of the unicasttransmission PAs with outputs of the broadcast transmission PAs to allowthe sharing of antennas in a M-MIMO array 813. M-MIMO array 813 may have8 or more transmit antennas. The broadcast transmission PAs may beconfigured to also make unicast transmissions when not making broadcasttransmissions. Communications device 800 also includes a receiver 825that is configured to receive frames, and the like.

A controller 820 is configured to control the state of PAs, such asbroadcast transmission PAs, to enable the turning on and off of the PAsto save power when the PAs are not being used to make transmissions. Ascheduler 822 is configured to select a subset of active UEs. A memory830 is configured to store broadcast information, unicast information,PA state, and the like.

The elements of communications device 800 may be implemented as specifichardware logic blocks. In an alternative, the elements of communicationsdevice 800 may be implemented as software executing in a processor,controller, application specific integrated circuit, or so on. In yetanother alternative, the elements of communications device 800 may beimplemented as a combination of software and/or hardware.

As an example, receiver 810 and transmitter 805 may be implemented as aspecific hardware block, while controller 820 and scheduler 822 may besoftware modules executing in a microprocessor (such as processor 815)or a custom circuit or a custom compiled logic array of a fieldprogrammable logic array. Controller 820 and scheduler 822 may bemodules stored in memory 830. Alternatively, controller 820 may beimplemented as a hardware block in transmitter 805.

Although the present disclosure and its advantages have been describedin detail, it should be understood that various changes, substitutionsand alterations can be made herein without departing from the spirit andscope of the disclosure as defined by the appended claims.

What is claimed is:
 1. A method comprising: receiving, by a userequipment (UE) from a base station, over a first set of frequencysub-bands of a frequency band during a first time interval, a broadcastsignal amplified by a first set of power amplifiers (PAs) in atransmitter antenna array of the base station; receiving, by the UE fromthe base station, over a second set of frequency sub-bands of thefrequency band during the first time interval, a unicast signalamplified by a second set of PAs in the transmitter antenna array of thebase station, the first set of PAs being disjoint from the second set ofPAs; receiving, by the UE from the base station, during a second timeinterval, a third signal amplified by the first set of PAs in thetransmitter antenna array without receiving the broadcast signal;receiving, by the UE from the base station, during the second timeinterval, the unicast signal; and processing, by the UE, the receivedbroadcast signal and the received unicast signal.
 2. The method of claim1, further comprising receiving the broadcast signal and the unicastsignal in different frequency bands.
 3. The method of claim 1, theunicast signal being beamformed and specific to the UE.
 4. The method ofclaim 1, further comprising simultaneously receiving the broadcastsignal and the unicast signal during a third time interval.
 5. Themethod of claim 1, the first set of frequency sub-bands being disjointfrom the second set of frequency sub-bands.
 6. The method of claim 1,further comprising receiving the unicast signal during a third timeinterval, without receiving the broadcast signal during the second timeinterval.
 7. The method of claim 6, further comprising receiving theunicast signal over both the first set of frequency sub-bands and thesecond set of frequency sub-bands during the third time interval.
 8. Auser equipment (UE) comprising: an antenna configured to: receive, froma base station, over a first set of frequency sub-bands of a frequencyband during a first time interval, a broadcast signal amplified by afirst set of power amplifiers (PAs) in a transmitter antenna array ofthe base station; receive, from the base station, over a second set offrequency sub-bands of the frequency band during the first timeinterval, a unicast signal amplified by a second set of PAs in thetransmitter antenna array of the base station, wherein the first set ofPAs is disjoint from the second set of Pas; receive, from the basestation, during a second time interval, a third signal amplified by thefirst set of PAs in the transmitter antenna array without receiving thebroadcast signal; and receive, from the base station, during the secondtime interval, the unicast signal.
 9. The UE of claim 8, wherein theantenna is configured to receive the broadcast signal and the unicastsignal in different frequency bands.
 10. The UE of claim 8, wherein theunicast signal is beamformed and specific to the UE.
 11. The UE of claim8, wherein the antenna is configured to simultaneously receive thebroadcast signal and the unicast signal during a third time interval.12. The UE of claim 8, wherein the first set of frequency sub-bands isdisjoint from the second set of frequency sub-bands.
 13. The UE of claim8, wherein the antenna is configured to receive the unicast signalduring a third time interval, without receiving the broadcast signalduring the third time interval.
 14. The UE of claim 13, wherein theantenna is configured to receive the unicast signal over both the firstset of frequency sub-bands and the second set of frequency sub-bandsduring the third time interval.